Fuel injection pump

ABSTRACT

A fuel injection pump having two kinds of plungers rotatable by a common rack, one kind for supplying fuel and the other for ceasing fuel supply during the idling of an engine, comprising plungers for ceasing fuel supply during the idling of the engine, vertical grooves of metering helical grooves of said plungers being changed in width successively.

United States Patent Kawase et a1.

[ Dec. 30, 1975 1 1 FUEL INJECTION PUMP [75] lnventors: Koichi Kawase, l-ligashi-Matsuyama;

Yasuhide Suzuki, Saitama, both of Japan [73] Assignee: Diesel Kiki Kabushiki Kaisha, Japan [22] Filed: Apr. 29, 1974 [21] Appl. No.: 465,349

[30] Foreign Application Priority Data May 7, 1973 Japan 48-S2638[U] [52] US. Cl 123/139 R; 123/139 AB; 123/139 AC [51] Int. Cl. F02M 39/00 [58] Field of Search... 123/139 R, 139 AC, 139 AB, 123/139 AD, 32 G [56] References Cited UNITED STATES PATENTS 2,050,134 4/1936 Thomas 123/139 R 2,810,375 10/1957 Froehuch 123/139 R 3,435,811 4/1969 Guertler 123/139 R 3,438,327 4/1969 Thompson v 123/139 R 3,677,256 7/1972 Regneault 123/139 AC 3,792,692 2/1974 Kiley 123/139 AB Primary ExaminerCharles J. Myhre Assistant Examiner-Daniel J. OConnor Attorney, Agent, or Firm-Larson, Taylor and Hinds [5 7] ABSTRACT A fuel injection pump having two kinds of plungers rotatable by a common rack, one kind for supplying fuel and the other for ceasing fuel supply during the idling of an engine, comprising plungers for ceasing fuel supply during the idling of the engine, vertical grooves of metering helical grooves of said plungers being changed in width successively.

1 Claim, 4 Drawing Figures US. Patent Dec. 30, 1975 I F|G.4

FIG.

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RACK POSITION FUEL INJECTION PUMP The present invention relates to a fuel injection pump for an injection type internal combustion engine, par- 5 In these days, Diesel engines for vehicles tend to I operate at high speed due to increase of engine output and are so designed that range of number of revolutions from a minimum number of revolutions to a maximum number of revolutions is widened so as to obtain sufficient air supply and compression heat at a maximum speed and at a maximum load. On the other hand, in order to reduce exhaust gases which lead to public hazards, it is required to carry out an accurate and regular combustion even when the engine is idle. However, the aforesaid design makes it difficult to meet such requirements during the idling of the engine.

Thus, in the known devices, as disclosed in Japanese Patent Publication No. 50886/72 and Japanese Patent Specification No. 154,906, there is automatically ceased fuel supply to some of a plurality of cylinders in the engine so as to obtain better combustion when the engine is idle and fuel more than a quantity of the fuel previously supplied is supplied to the rest of the cylinders so that number of actually-operated cylinders in the engine is decreased and temperature of the rest of actually-operated cylinders is raised by increase of a' quantity of fuel, thus improving combustion. This construction is of a multi-plunger type and provides an injection pump adapted to control a quantity of injected fuel by a rack which controls in common rotational position of each of plungers and a metering helical groove in the periphery of each plunger, wherein the fuel supplied cylinders and the fuel supply ceased cylinders when the engine is idle, have different shapes of metering helical grooves in the plungers corresponding to said cylinders, respectively, thereby supplying fuel and ceasing fuel supply. However, in a case where the fuel injection is carried out in a manner as de scribed above, if number of revolutions of the engine is increased from number of revolutions in an idling state, the rack is slightly displaced at the time when the fuel is supplied into the fuel supply ceased cylinders so that a quantity of fuel is rapidly increased, causing to bring about disadvantages such as hunting of the engine.

An object of the invention is to eliminate the above. disadvantages and to obtain a fuel injection pump wherein fuel supply may be ceased for desired cylinders during the idling of the engine to thereby provide a smooth idling operation and to smoothly increase number of revolutions of the engine from the idling one, which could not be attained by prior arts, in addition to the prior arts that reduces discharge of exhaust gases and a great effect is offered in the accomplishment of smooth operation of the whole range of number of revolution of the engine.

According to the present invention, a fuel injection pump comprising metering grooves in a plurality of in ection pump plungers for ceasing fuel supply, widths of vertical portions in communication with a plunger pump chamber are successively changed to orderly effect the feeding of fuel into the fuel supply ceased cylinders thus smoothly increasing the number of revolutions of the engine from number of revolutions in an idling state.

The present invention will now be described with reference ,to the accompanying drawings, in which:

FIG. 1 is a sectional view of a plunger in a Bosch type fuel injection pump,

FIG. 2 is a diagram showing relation between fuel quantity and rack position, and

FIGS. 3 and 4 are sectional views of further plungers similar to that shown in FIG. 1 but wherein the width of the vertical or longtidunal groove formed in the plunger is varied.

In conventional fuel injection pumps such as illustrated, for example, in U.S. Pat. No. 3,438,327, two different groups of plunger assemblies are provided, viz., a first group of plungers which are designed to terminate fuel during idling and a second group of plungers which provide continuous fuel flow during idling. In all instances the plunger assemblies of the former group include a so-called helical groove which provides a control edge, and a vertical groove which is connected to the helical groove in the idling region of the latter, i.e., in the region of the portion of the control edge which is moved to an operative position relative to the inlet port during engine idling.

Thus, referring to FIG. 1, a helical groove G and a vertical groove 1 are shown which are of conventional form and correspond to those discussed above. In the exemplary embodiment illustrated in FIG. 1, the vertical groove 1 indicated in solid lines represents the groove that would be employed in a plunger used to terminate fuel flow during idling while groove 2 indicated in dashed lines would be employed in a plunger in which fuel is supplied throughout idling. The plunger P in which grooves G and 1 are formed moves within a chamber C relative to an inlet port IP to control the fuel between inlet port IP and an outlet or discharge port OP. The time during which fuel is supplied is controlled by acam shaft (not shown) which raises and lowers plunger P so as to vary the position of the control edge of helical groove G relative to inlet port IP. In accordance with conventional operating procedures, the angular position of plunger P is controlled by a rack (not shown) in common with the other plungers of the pump so that the amount of fuel supplied by the pump is varied, and equal amounts of fuel are supplied to each cylinder. FIG. 1 illustrates the bottom of the stroke of plunger P wherein fuel is supplied to the portion of chamber C formed above plunger P but is prevented from escaping therefrom by a check valve (not shown) positioned in outlet port OP. This valve is open during the compression upstroke of plunger P so that fuel is discharged through outlet port OP at this time. Fuel flow is terminated on the downstroke of plunger P and it will be appreciated that with plunger P rotated to the idling position, wherein the upper portion of the helical groove G adjacent to vertical groove 1 registers with inlet port IP, the amount of fuel injected will be reduced since the fuel pressure above plunger P will be communicated to inlet port IP sooner (i.e., the inlet opening of port IP will be uncovered sooner) during the downward movement of plunger P than would be the case when plunger P is rotated to the position shown in FIG. 1.

Referring now to FIG. 1, in a conventional construction a width (a) of vertical or longitudinal groove 1 in a plunger for ceasing fuel supply during the idling of an engine is formed greater than a width (b) of longitudinal groove 2 in a plunger for supplying fuel during the idling of the engine to such extent that the portion of the width (a b) thus cut corresponds to the lead portion during the idling of the engine. Thus, the injection pump plungers provided with two kinds of longitudinal grooves having the groove widths (a) and (b) are suitably combined in accordance with number of cylinders in the engine, for example at the ratio of 3 to 3 in case of a six-cylinder, and, as noted, are rotated by a common rack to increase or decrease fuel supply, and the object was obtained by the characteristic line A of injection amount obtained by the plunger provided with a longitudinal groove having the width (a) and the characteristic line B of injection amount obtained by the plunger provided with a longitudinal groove having the width (b), as depicted in FIG. 2. However, in the arrangement as described above, the total amount of the fuel to be supplied into the engine was rapidly changed in the vicinity of a point of intersection 3 of the characteristics lines A and B of injection amount shown in FIG. 2, causing the disadvantages such as hunting of the engine.

In accordance with the present invention, longitudinal grooves l, l, and l in the plungers for ceasing fuel supply during the idling of the engine are configured in widths successively changed as shown at a, a, and a in FIGS. 1, 3 and 4 and these plungers are used in order to obtain the characteristic lines A, A and A", as shown in FIG. 2, so as to have points of intersection in the plural positions shown as at 3', 3", while only one point of intersection 3 has heretofore been provided between the characteristic line of injection amount of the plungers for supplying fuel during the idling of the engine and the characteristic line of injection amount of the plungers for ceasing fuel supply,

thereby providing a gradual change in the total amount of the fuel to be supplied into the engine and preventing the occurance of hunting in the engine.

While the number of plungers provided with the longitudinal grooves for ceasing fuel supply during the idling of the engine has been indicated as at three characteristic lines A, A and A of injection amount as shown in FIG. 2 in the preferred embodiment, this number may be plural to meet requirements for an engine, and it is evident that various combinations may be made, for example, the characteristic lines A and A of injection amount are made identical and the characteristic A of injection amount is to have a predetermined characteristic of injection amount. Many variations may be effected without departing from the spirit of the invention.

What is claimed is:

1. In a fuel injection pump comprising a plurality of pump devices each including a chamber and a plunger slidably disposed in oil tight relationship within the chamber, each said plunger including a helical'control edge formed thereon which cooperates with a port in the chamber to control the amount of fuel supplied, said pump devices being controlled from a common fuel rod, and a plurality of said plungers including a vertical fuel supply groove which opens at the top of the plunger and is connected to the helical control edge at a portion of the latter which corresponds to the engine idling position, the improvement wherein the width of the vertical groove is varied for each said plunger so as to provide a predetermined variation in the total amount of fuel to be supplied to the engine. 

1. In a fuel injection pump comprising a plurality of pump devices each including a chamber and a plunger slidably disposed in oil tight relationship within the chamber, each said plunger including a helical control edge formed thereon which cooperates with a port in the chamber to control the amount of fuel supplied, said pump devices being controlled from a common fuel rod, and a plurality of said plungers including a vertical fuel supply groove which opens at the top of the plunger and is connected to the helical control edge at a portion of the latter which corresponds to the engine idling position, the improvement wherein the width of the vertical groove is varied for each said plunger so as to provide a predetermined variation in the total amount of fuel to be supplied to the engine. 